Color process using cellulose ester emulsions



April 1942- J. A. LEE-RMAKERS ET AL 2, O v

COLOR PROCESS USING CELLULOSE ESTER EMULS IONS Filed Dec. 26, 1940 HYDROLIZED CELLULOSE ORGANIC ACID ESTER GELATIN COUPLER SILVER HALIDE SUPPORT .JDHN A.LEERMAKE'R5 EEI'HEURINE- 5.FIERKE IN EN'IIORS XA/ua/a A TTORNEYS tion to provide a method for gelatin is water-soluble, it does not Patented Apr. 14, 1942 UNITED STATES PATENT OFFICE COLOR PROCESS U ZzlZ CELLULOSE ESTER John A.

Rochester, N. Y.,

Company, Rochester,

New Jersey Leer-makers and Scheuring S. Fierke,

assignors to Eastman Kodak a corporation of Application December 26, 1940, Serial No. 371,650 In Great Britain December 29, 1939 5 Claims.

This invention relates to color photography and particularly to light sensitive cellulosic emulsions having color formers therein.

In Mannes and Godowsky U. S. application Serial No. 314,689, filedJanuary 19, 1904, there are described Photographic emulsions in which couplers or color-forming compounds are mixed with cellulose esters and the mixture dispersed in gelatino-silver halide emulsions. This method of preparing emulsions for use in color photography depends on the use of immiscible phases so that a dispersion of the cellulose ester in the gelatin can be formed. It cannot be used for the preparation of photographic emulsions in which a cellulose ester is the carrier for the silver halide; since the cellulose 'ester used to dissolve the gelatin would be soluble in the cellulose ester used to disperse the silver halide and a dispersion of one cellulose ester in the other could not be formed.

It is, therefore, an object of the present invenincorporating couplers or color-forming compounds in cellulose ester emiulsions. Other objects will appear from the following description of our invention.

These objects are accomplished by forming a the coupler in gelatin and dispersing this dispersion in a water-permeable cellulose organic acid ester containing sensitive silver halide grains.

The single figure of the accompanying drawing is a sectional view of a single layer photographic element formed according to our invention.

The invention relates to colored photographic elements of the type in which a support, which may be of transparent material such as cellulose nitrate or cellulose acetate, or of opaque or translucent material such as paper, carries one or more sensitive photogra hic emulsions containing silver halide grains dispersed in a cellulose ester. The cellulose ester is one which is permeable to photographic processing baths, suchas photographic developing and fixing solutions. In this emulsion there is dispersed gelatin particles containing color-forming or coupling compounds. By reason of the fact that the cellulose ester of the silver halide emulsion but, "under the proper conditions, form'sa dispersion in the sensitive emulsion. The colorforming compounds incorporated in the gelatin particles are of the well-known type containing incorporated mix with F reactive thylene or phenolic hydroxyl groups and are capable of combining with the oxidation product of a primary aromatic amino developing agent upon photographic development to form a colored image. Metallic silver is formed simultaneously with the production of the colored image and this silver may be subsequently removed without removal of the dye, leaving substantially clear, transparent dye images.

The cellulose esters suitable for formation of the emulsions used in our invention are preferably hydrolyzed cellulose organic acid esters such as those described in Salo U. S. Patent 2,110,491, granted March 8, 1938. These esters have an acyl content of from about 19% to about 33, preferably 19% to 26%.

Our invention may be used for the formation of photographic images of a single color in a single photographic layer or for the formation of natural color images in multi-layer photographic coatings. The cellulose ester emulsions may be sensitized with optical sensitizers in the wellknown manner so of the esters to blue light may be extended into the green and red spectral regions.

Our invention will be understood by reference to the following examples which illustrate the formation of color-forming emulsions according to our invention:

Example 1 To 200 cc. of a 10% gelatin solution in water there was added 0.8 cc. of sodiumihydroxide and to this alkaline gelatin solution there were added with rapid stirring 4 grams of a solution of z-lauryli-chlorophenol in 20 cc. of ethyl alcohol containing 2 cc. of sodium hydrozide. Following the addition of the coupler, 8.4 cc. of

Ethylene chloride; cc l8 Ethyl alcohol cc 2 Cellulose acetate propionate gram 0.5

Silver bromide do After the addition of the gelatin-coupler. dispersion, the emulsion was further diluted with 20 that the natural sensitivity.

tions and therebyto incre cc. oi ethylene chloride in order to decrease I viscosltm.

a suitable amount of -4-(3-ethyl-2-(3) -be'nzothiazolilidine) 2 butenylidene phenyl-z-thiohydantoin was used.

inone amino known red sensitizers but in the present case After addition oi the coupler-gelatin dispersion to the emulsion, the emulsion was passed through a colloid mill or homogenizer to form a dispersion of gelatin in theemulsion and was then coated on a suitable support.

Example 2 A green-sensitive emulsion was prepared in the same manner as described in Example 1, except that a green sensitizer and a coupler capable of yielding a magenta dye upon development were used. The emulsion was sensitized to green light with 5-(3-ethyl-2-(3) -benzoxa'zolylidene) -ethylidene- 3 -m-heptyl 1 phenyl 2- thio-hydantoin. The coupler used in this case was 2 cyanoacetyl 5 (p sec. amyibenzoylamino) -coumiarone Example 3 An emulsion was prepared in the same manner as described in Example 1 except that it n was not specially sensitized and a coupler capable oi yielding a yellow image upon photographic development was used In this case the coupler was n-propyl-p-benzoylacetaminobenzenesulfonate.

Example 4 In addition to the single layer coatings, the red sensitive emulsion prepared as described in Example 1 was coated on a transparent support and over it there was coated the green sensitive emulsion prepared as described in Example 2. Upon suitable exposure and development this multi-layer coating yielded a blue-green image in the bottom emulsion layer and a magenta image in thetop emulsion layer.

Instead. of the 33% acyl cellulose acetate propionate described in the examples, the coupler dispersion in gelatin may also be added to a farhydrolyzed cellulose acetate propionate emulsion in which the acyl content is as low as 19 to 20%. This may be coated either sensitized orunsensitized. The coating thus prepared is much more permeable to water than is that in which the vehicle for the silver halide emulsion is a cellulose organic acid ester of 33% acyl content.

However, in the case of the cellulose organic acid esters of 19-20% acyl content, the cellulose ester is more readily precipitated from solution by the addition of water or aqueous solutions so that with this ester the amount :of coupler which may j be added to the emulsion is of the orderof 10 to 20% of that which may higher acyl cellulose-esters.

In the case of ;the emulsions of higher acyl be used withthe .content whose water permeability is' relatively low. porosity modifiers may be added to increase the permeability of the ester to processingsoluase the amount of dye formed. Gompounds suitable for this .are the porositymodii lers described lnMannes are more stable than the ylenediaminehydrochloride and Godowsky U. 8. application Serial No. 314,- 689, filed January 19, 1940.

Emulsions made 'according to our invention may be developed with any suitable solution of a primary aromatic amino developing agent such as p-phenylenediamine and its substituted derivatives. The compounds which we prefer to use are dialkyl-p-phenylene diamines substituted group. the other amino group remaining unsubstituted. These compounds are ordinarily used in the salt iorm such as the hydrochloride or sulfate since these compounds amines themselves. Developing agents which may be used include diethyl-p-phenylenediamine, monomethyl-p-phenand diethyl-p-phenylenediamine-sulfate.

' The developer used for coatings made with low acyl (19-20% content) cellulose acetate propionate-silver halide emulsions may have the following composition:

2 amino 5 diethylamino t o l u e n e HCl .grams 2.0 Sodium sulflteni do- 2.0 Potassium bromide -do 2.0 Sodium carbonate do 20.0 Water to make -cc. 1000.0

This developer was found to produce good color in 10 to 15 minutes? development.

Photographic coatings described -in the speciiic examples using a cellulose acetate propionate of about 33% acyl content require a more energetic developer such as one having the 101-" lowing composition:

Sodium suliite grams 15.0 2 a min 0 5 diethylamino toluene HCl grams 2.0 Kodalk 0---- 50.0 Sodium hydroxide 'do 0.5 G-nitrobenzimidazole do 0.01 Potassium bromide do- 2.0 Water to make cc 1000.0

4 pounds such as benzyl'alcohol, acetone, etc. to

increase the permeability of these layers.

Reference will now be had to the accompanying drawing which further illustrates our invention. As shown therein, a support l0 of any suitable material such as glass. cellulose ester. synthetic resins or paper, has coated thereon a layer ll of hydrolyzed cellulose organic acid ester containingsilver halide particles l2 and dispersed particles ll of gelatin containing coupler. Multi-layer coatings .may be madein a similar way and may be superimposed on the same side or onopposite sides oi a support. In the case of a 3-layer' coating oi superposed layers on one side of a support the outer layer will usuallybe blue-sensitive,.the middlelayer green-sensitive. andthe innermost layer red sensitive in the well .known manner. In this case-the-customar-y yellow filter layer will be aromatic amino photographic layer, which comprises mixing, in

tion of blue lighten the green sensitive layers and the red sensitive layers during the exposure of the element.

Our process possesses diilusion of the couplers in reduced by incorporating the coupler in gelatin, and fading of the resulting dye images is found to be decreased.

The examples and modifications included in the present specification are illustrative only and modifications may be made in our process within the scope of the appended claims.

We claim:

1. The method of producing a color-forming photographic layer, which comprises mixing, in alkaline solution, gelatin compound capable of reacting with a primary aromatic amino developing agent on photographic development, acidifying the solution to form a fine dispersion of the color-forming compound in the gelatin, and dispersing the gelatin and color-forming compound in a water-permeable cellulose ester-silver halide emulsion.

'2. The method of producing a color-forming photographic layer, which comprises mixing, in alkaline solution, gelatin with a color-forming compound capable of reacting with a primary developing agent on photographic development, acidifying the solution to the advantages that 'form a fine dispersion of the color-forming comdispersing the gelatin pound in the gelatin, and and color-forming compound in a water-permeable cellulose organic acid ester-silver halide emulsion.

3. The method of producing a' color-forming 35 the emulsion may be with a color-forming pound in the gelatin,

alkaline solution, gelatin with a color-forming compound capable of reacting with a primary aromatic amino developing agent on photographic development, acidifying the solution to form a fine dispersion of the color-forming comand dispersing the gelatin and color-forming compound in a water-permeable cellulose acetate propionate-silv'er halide emulsion.

4. The method of producing a color-forming photographic layer, which comprises mixing, in alkaline solution, gelatin with a color-forming compound capable of reacting with a primary aromatic amino developing agent on photographic development, acidifying the solution to form a fine dispersion of the color-forming compound in the gelatin, and dispersing the gelatin and color-forming compound in a water-permeable cellulose acetate propionate' of approximately 33% acyl content.

5. The method of producing a color-forming photographic layer, which comprises mixing, in alkaline solution, gelatin with a color-forming compound capable of reacting with a primary aromatic amino developing agent on photographic development, acidifying the solution to form a fine dispersion of the color-forming compound in the gelatin, and dispersing the gelatin and color-forming compound in a water-permeable cellulose acetate propionate of approximately 20% acyl content silver halide emulsion.

JOHN A. LEERMAKERS. SCHEURING s. FIERKE. 

